Among other things, we will discuss both fuse ratings and circuit breaker ratings. Dec 14, 2016 this feature is not available right now. The curves are a logarithmically graphical representation of the performance characteristics of the devices at a base voltage of 480 volts. If the fault is still present, the automatic circuit recloser operates more slowly than the fuse, enabling the fuse to clear. We suggest noting on the panel schedule the siemens breaker suggested by the tool and calling for an equivalent product for other approved manufacturers.
See arc flash values changeon the flyas protective device settings are adjusted. How to perform coordination study of ocpd and cable in electrical design. Whats really needed is an inexpensive software program for short circuit and coordination studieseither on a cd, or available online so anyone can access and use it. Overcurrent coordination page 3 qualtech engineers, inc. Low voltage breaker low voltage breaker coordination requires only that. The curves below figures 12 and, will show the differences in this deadband for the same circuit breaker using an electronic versus nonelectronic trip mechanism. The next several pages cover selective coordination from various perspectives. Evaluating selective coordination between currentlimiting fuses and non currentlimiting circuit breakers. Selective coordination with circuit breakers iaei magazine. Automated selective coordination of circuit breakers youtube. A fuse is a device, which is used to protect circuits from over current, overload and make sure the protection of the circuit. Coordination between the operating characteristics of two or more overcurrent protection devices, so that when an overcurrent within established limits occurs, the device. Apr 06, 2011 presented by chuck nochumson and dave loucks. Total integration of all momentary, interrupting, and relay shortcircuit and arc flash results with the oneline and protective devices.
Any or all of these parameters may be entered to narrow the search results. Figure 29 shows a 400a fuse with downstream 100a circuit breaker. This type of coordination is therefore mainly used in end distribution with low rated current and shortcircuit current values and high impedance of the connection cables. Generate short circuit, devise settings, sqop reports. Difference between relay and circuit breaker characteristics of fuse and circuit breaker. Design of protection coordination of a distribution. For circuit breakers, if there is an overlap of the tccs below the available short circuit current at the downstream bus, then the circuit breaker selective coordination tables.
The main purpose of the protective coordination software is to produce oneline diagrams, calculation of relay settings and time current coordination drawings. Bothe fuse and circuit breaker are rated in amperes which can be seen on its nameplate which is known as rated current or nominal current. Electrical engineers use powertools to perform harmonic analysis, transient stability analysis, short circuit analysis, and to determine demand load, voltage drop, arcflash hazard analysis and protective device coordination. Notice the difference in the tolerance in the trip curve of the feeder circuit breaker. Selective coordination is required for systems related to life safety as defined in the nec, and is achieved when an overcurrent on a circuit is interrupted and only the closest upstream device opens such that only the section of the electrical system with a problem is taken offline. Ecoord fuse and breaker coordination huge builtin library of devices. Fuse ratings lv circuit breaker ratings, characteristics, and. Software will contain features to model various protective devices, equipment damage curves and store the data for future use.
Other times, the design engineer will use the software with which he or she is. The proper selection and coordination of protective devices is mandated in article. How to achieve selective coordination of circuit breakers eep. Nov 02, 2016 for circuit breakers, if there is an overlap of the tccs below the available short circuit current at the downstream bus, then the circuit breaker selective coordination tables must be employed. The 90 ampere breaker generally unlatches before the 400 ampere breaker. Ecoord fuse and breaker coordination elite software. Jun 28, 2018 generate short circuit, devise settings, sqop reports. Protective device coordination software key features. Overcurrent coordination setting guidelines transformers skm. This tool provides circuit breaker selections that are fully rated and fully selective. Features and benefits of the ch dinrail mount modular fuse holders for class cc, midget iec 10x38 and 10x38 pv fuses. Circuit breaker ratings include these same factors, but unlike fuses, they are resettable after a trip incident. Selectivity among fuses or between fuses and circuit. They comprise multiple tables for main or upstream and branch breakers.
Ecoord gets the job done right when it comes to analyzing timecurrent curves for overcurrent protection devices. If the system you are designing requires selective coordination, then that is what specifications should state, not coordinated to 0. Search all the circuit breakers that can be selective with a defined circuit breaker. Circuit breaker ratings include these same factors, but unlike fuses, they are. Choosing a circuit breaker with a trip curve that trips too soon can result in nuisance tripping. How to achieve selective coordination of circuit breakers. The reason for this difference is that in the case of the fuse and lowvoltage breaker, there is a delay caused. Selective coordination circuit breakers current in amperes 100 200 300 400 600 800 2000 3000 4000 6000 8.
Electrical calculation tools is a set of 7 computer aided online tools designed to help you. Mar 15, 2016 selective coordination requires that only circuit breaker one clear the fault, allowing the other breakers in the switchboard identified as nsg to continue normal operation. Selective coordination applies for the full range of overcurrent on the system and the full range of overcurrent interrupting times associated with those overcurrents. Low voltage breaker fuse coordination requires a minimum 0. Timecurrent curves circuit breakers no action to left of curve trip or clear on and to right of curve. Oct 01, 2007 so, the implication is that many of the coordination studies probably just dont get done. For example, schneider electric has an excellent piece of software. Understanding time current curves maverick technologies. By the aid of a computer software or by manual process make the. It can be seen the coordination is done in such a way that circuit breaker 4 has to operate first followed by fuse and finally relay. The same applies to short circuit studies, he adds. Choosing a circuit breaker that trips too late can result in catastrophic damage to machine and cables. Coordination is required for over current protective devices for essential electrical systems in healthcare facilities. The curve below shows a 90 ampere circuit breaker and an upstream 400 ampere circuit breaker with an instantaneous trip setting of 5 5 times 400a 2000a.
With builtin data for over 2,000 individual devices already builtin, all you have to do is select the devices you want from the list and youre ready to go. In the fuse saving mode, the automatic circuit recloser or reclosing breaker operates a couple of operations faster than a fuse, trying to clear a momentary fault. How to design selectivity in the overload and in the shortcircuit zone fuse fuse. To ensure full selectivity between the upstream fuse and the downstream circuitbreaker, we recommend replacing the upstream fuse after clearance. What is the difference between fuse and circuit breaker. Fuses and circuit breakers operation and coordination. Device coordination getting started with etap star youtube.
Selective coordination generally describes the design of an electrical system in which the upstream protective device fuse or circuit breaker nearest to the system fault clears the fault without affecting the protective devices that are upstream from it. In electric power distribution, a recloser, or autorecloser, is a circuit breaker equipped with a mechanism that can automatically close the breaker after it has been opened due to a fault. Guide to power system selective coordination 600v and below. In the example on the right with breaker coordination, the breaker. Circuit breaker timecurrent characteristic curves are read similar to fuse curves. Circuit breaker operation similar to a fuse, a circuit breaker is a device designed to open an electrical power circuit, under. We need to coordinate ocpd and cable to ensure that during fault condition the circuit breaker or fuse will clear the system before the conductor start burning that would trigger an arc flash or fire. Reclosers are used on overhead distribution systems to detect and interrupt momentary faults. Distribution panel circuit breaker and fuse plotting. Shortcircuit study an analysis of available fault currents in the power system is performed. To achieve selective coordination with fuses, the fuse ratio tables must be employed. Provides guidance to engineers regarding the national electrical code nec requirements for selective coordination. Circuit breaker detects failures and prevents the application from trying to perform the action that is doomed to fail until its safe to retry.
The bussmann series fuse selector tool is an online application that will help you select a bussmann series fuse based upon fuse characteristics. Up to date with schneider electric low voltage protection devices and circuit breakers. Some circuit breaker manufacturers provide tested coordination tables that may be used in. Frequently asked questions about selective coordination. Breaker curvesincluding solidstate trips, electromechanical trips, thermalmagnetic trips, and motor circuit protectors. For shortcircuit currents at that crossover point and higher, the upstream fuse is not coordinated with the down stream circuit breaker. Compared with a coordination of the time type, the need to. Coordinating fuses with molded case breakers mike holts. The minimum instantaneous unlatching current for the 400a circuit breaker could be as low as 2000a times.
Fuse ratings include current which is, after all, what causes fuses to open, voltage, amps interrupting capacity, and other items. A circuit breaker left and class l fuse right usa t 978 462 6662 f 978 462 0181 info. Display the timecurrent curves of 1 to 8 circuit breakers. Selective coordination of lowvoltage circuit breakers. Main keywords for this artile are protective device coordination analysis, circuit breaker coordination, shortcircuit coordination, fuse to fuse coordination, relay coordination procedure. Thank you for your interest in selective coordination designer v1.
This protection device may be a fuse or another circuit breaker. Facilities instructions, standards, and techniques volume 39 methods for coordinating system protective equipment internet version of this manual created september 2000 facilities engineering branch denver office denver, colorado the appearance of the internet version of this manual may differ from the original, but the contents do not. When drawing circuit breaker timecurrent curves, determine the proper interrupting rating from the manufacturers literature and represent this interrupting rating on the drawing by a vertical line at the right end of the curve. Fuse ratings lv circuit breaker ratings, characteristics, and settings. Tripping sequence and tripping time of devices were observed. Our selective coordination lookup tables are quick and easy to use. Available fault current selective coordination spreadsheet. Protective device coordination analysis paktechpoint. The other circuit breakers in the switchgear would not see the fault. This easypower webinar, taught by satish shrestha at easypower, will cover the use of easypower to perform automated selective coordination of circuit breakers. Display the timecurrent curves of 1 to 8 circuitbreakers.
Guide to power system selective coordination 600v and below document number 0100db0603 2. Check the discrimination between two circuitbreakers and display their timecurrent curves. The example on the left lacks breaker coordination. The software to view directly coordination between devices. Check the discrimination between two circuit breakers and display their timecurrent curves. Faster than the heavy full features electrical network calculation software. The minimum instantaneous unlatching current for the 400 a circuit breaker could be as low as 2000 a times. The program performs a search based upon electrical or electronic fuse, the voltage rating, ac or dc, timedelay or fastacting characteristics, and the amp range, fuse class, fuse family, fuse series, fuse body type, size and even application. Selective coordination selective coordination cooper bussmann. The curve below shows a 90ampere circuit breaker and an upstream 400ampere circuit breaker with an instantaneous trip setting of 5 5 times 400 a 2000 a.
The following curve illustrates a typical thermal magnetic molded case circuit breaker curve with an overload region and an instantaneous trip region two instantaneous trip settings are shown. Selectivity among fuses or between fuses and circuit breakers. Cyme power engineering software protective device analysis. Computer programs allow the designer to select timecurrent curves. If a fault above 1500 amperes occurs on the load side of the 90 ampere breaker, both breakers could open. Protective device coordination analysis, circuit breaker coordination, shortcircuit coordination, fuse to fuse coordination, relay coordination procedure. To display tripping curves and give the discrimination limit. Selective coordination requires that only circuit breaker one clear the. Frequently asked questions about selective coordination email 1951 0 tweet. We need different trip curves in order to balance the right amount of overcurrent protection against optimal machine operation. This paper specifically addresses how to comply with these requirements for lowvoltage circuit breakers. We know that both fuse and circuit breaker having the same rated current say 30a will not trip when more than 30a say 32 is flowing through them. Proprietary software systems for determination of selectivity are available, working from timecurrent data supplied by individual manufacturers.
The elite software ecoord program aids in the selective coordination of fuses and circuit breakers by providing an. Selective coordination requires that only circuit breaker one clear the fault, allowing the other breakers in the switchboard identified as nsg to continue normal operation. Packaged with a host of additional features, this electrical software configuration makes pdc and short circuit analysis a snap. Implementations of the circuit breaker design pattern need to retain the state of the connection over a series of requests. The coordinaide protection and coordination assistant software lets you quickly and easily select the optimal protective device e. When a short circuit or overload occurs, upstream breakers are tripped, unnecessarily knocking out circuits and equipment, which also makes it more difficult for maintenance personnel to locate the source of the fault. This is the zone in which the thermal protection for thermomagnetic releases and protection l for electronic releases are normally called on to intervene. This is the zone in which the thermal protection for. The inclusion of selective coordination in the nec since the 2002 revision and the expansion of. The siemens selective coordination tool will identify commonly used siemens circuit breakers whose trip curves do not overlap for the conditions selected by the engineer. Protect transformers against damaging overcurrents and coordinate with primary and secondaryside protective. It can be seen the coordination is done in such a way that circuit breaker 4.
The siemens selective coordination tool is based on data for siemens circuit breakers that may or may not be similar to products by other manufacturers. Breaker curvesincluding solidstate trips, electromechanical trips, thermal magnetic trips, and motor circuit protectors. Tcc curves for fuse and circuit breakers were observed. The fuse link or fuse element is a thing metal strip made up of copper, silver, aluminum, zinc, or alloys. Standard iec 609472 on industrial circuit breakers deals with coordination between a. A circuit breaker coordination study is used to analyze the tripping times for the series of overcurrent devices being compared, generally from the source through the largest branch circuit device. For consulting and plant engineers, protective device coordination software is absolutely critical for ensuring personnel safety and maximizing system uptime. Now at the push of a button all your fuse and circuit breaker curves are plotted and displayed for your complete installation and its easy to adjust. Difference between fuse and circuit breaker electrical. Overcurrent device protection and coordination evaluation software.
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